How a tax break turns a smaller coupon into the bigger return
A bond’s headline yield only tells half the story once taxes enter the picture. The interest from a taxable bond is taxed at your top bracket, so a portion of every coupon goes to the government, while a tax-free municipal bond lets you keep the whole thing. To compare the two fairly you cannot line up their stated yields directly — instead you ask what pre-tax yield a taxable bond would need to leave you with the same money after tax. That gross-up is the tax-equivalent yield, and it is why a muni paying less on paper can still be the better deal. The size of the advantage depends entirely on your marginal tax rate. If you also want to confirm the yield a bond is actually paying at its market price, thecurrent yield calculatorworks that out from the coupon and price.
The tax-equivalent yield formula
Tax-equivalent yield = Tax-free yield ÷ (1 − marginal tax rate)
where tax-free yield is the muni’s stated yield andmarginal tax rate is the rate on your last dollar of income, written as a decimal. When the muni is also exempt from state and local tax, combine those rates with your federal rate; when it is only federally exempt, use the federal rate alone.
What makes this calculator different
- It grosses up the muni yield. Enter the tax-free yield and your marginal rate and it returns the tax-equivalent yield — the pre-tax number a taxable bond has to beat.
- It can compare a specific taxable bond after tax. Drop in a real taxable yield and the calculator nets it down for your bracket so you are comparing like with like.
- It gives you a clear winner. Rather than leaving you to eyeball two percentages, it tells you which bond comes out ahead for the rate you entered.
- It works with a combined federal + state rate. For an in-state muni that escapes state and local tax too, add those rates so the gross-up reflects the full tax you avoid.
Frequently asked questions
What is tax-equivalent yield?+
Tax-equivalent yield is the pre-tax yield a taxable bond would have to offer to match the after-tax return of a tax-free bond. Because municipal bond interest usually escapes income tax, a muni paying a modest coupon can beat a higher-coupon taxable bond once taxes are taken out. The formula grosses the tax-free yield up by your tax bracket: tax-equivalent yield = tax-free yield ÷ (1 − marginal tax rate). It puts both bonds on the same pre-tax footing so you can compare them apples to apples.
Why are municipal bonds tax-advantaged?+
Interest paid by most municipal bonds is exempt from federal income tax, and if you live in the state that issued the bond, it is often exempt from state and sometimes local tax too. This exemption exists to lower borrowing costs for states, cities, and other public issuers. The practical effect is that you keep more of a muni’s interest than you keep from an equivalent taxable bond, which is why munis appeal most to investors in higher tax brackets.
How do I find my marginal tax rate?+
Your marginal tax rate is the rate applied to your last dollar of income — the bracket your top dollar falls into, not the lower average rate you pay across all your income. It is the right rate to use here because the interest from a taxable bond stacks on top of your existing income and is taxed at that top bracket. Use your taxable income to identify the bracket that applies to the next dollar you earn. If you are unsure, a tax professional or your most recent return can help you confirm it.
Should I include state taxes?+
You should include state (and local) taxes when the municipal bond is also exempt from them, which is typically the case when you buy a bond issued within your own state. In that situation, use a combined rate that adds your state marginal rate to your federal marginal rate so the gross-up reflects the full tax you avoid. If the muni is only federally exempt — for example, an out-of-state bond — then use the federal rate alone. Matching the rate to the exemption keeps the comparison honest.
When does a taxable bond still win?+
A taxable bond can still come out ahead when your marginal tax rate is low, because the gross-up that boosts the muni’s equivalent yield is small. In the lowest brackets the tax you save on a muni is modest, so a taxable bond with a meaningfully higher stated yield can deliver more after tax. Credit quality, call features, and liquidity matter too, but on yield alone the muni’s edge shrinks as your bracket falls. Run both through the calculator with your actual rate before deciding.
Disclaimer: This calculator is foreducation and illustration only. Tax rules around municipal bonds are nuanced (the alternative minimum tax, state-specific exemptions, and how interest interacts with other items can all change the picture), and tax brackets change over time. Nothing here is investment, tax, or financial advice — confirm your own rate and situation with a qualified professional.